Multiple stage cementing



June 6, 1939. R4 E. oDoNNELl. 2,161,309

I MULTIPLE STAGE CEMENTING Filed Nov. 27, 1936 NVENTOR. ,2 E O'dormell BY Mr www.

A TTORNEY Patented June 6, 1939 PATENT OFFICE MULTIPLE STAGE CEMENTIN G Boland E. ODonnell, Odessa, Tex., assgnor to Halliburton Oil Well cementing Company,

Duncan, Okla.

Application November 27, 1936, Serial No. 112,950

v5 Claims.

This invention relates to the cementing of oil wells or the like, and more particularly to an arrangement for cementing longstrings of casing or. pipe in stages so that all of the cement which fills the annular space surrounding the casing may be supplied thereto without passing around the bottom'of the casing.

The multiple stage cementing of wells is now well known to those skilled in the art. 'I'he 0 method and apparatus for accomplishing this is fully disclosed in the United States patent to Halliburton, No. 1,860,669, granted May 31, 1932, and in the reissue thereof, No. 19,570, reissued May 14, 1935.

In the'multi-stage cementing of wells a valve structure, usually called aA multi-stage unit, is made up with the casing. The arrangement is such that at the proper time the valve in this unit is opened so that cement can flow outwardly therethrough to the annular space surrounding the casing. The valve may be a sleeve valve, as taught in the patents mentioned above, and may be openedgby one of the cementing plugs used in the multiple stage cementing operation.

As taught in the above mentioned patents, a multiple stage cementing operation usually employs several plugs. Thus, for example, in the illustration in Figs. 9 and 10 of the reissued Patent No. 19,570 two plugs travel through the multi-stage unit without a'ecting the same, a third plug enters the multi-stage unit and opens the valve and a fourth plug follows the slug of cement which ows through the multi-stage unit.

It sometimes happens in such a multi-stage cementing operation as that described that the plugs which are intended to pass through the multi-stage unit without opening the valve do not do so but become wedged therein and open the valve prematurely.

It is one object of the present invention to devise means insuring the proper operation of a multi-stage cementing apparatus to overcome the diiculty just mentioned.

It is a further object of the invention to provide means for scraping and cleaning a portion of a casing mounted.beneath a ymultiple stage unit to prevent cement from clinging thereto and interfering with subsequent operations in the well. In this connection it is to be noted that in a multiple stage system, as described in the aforementioned patents, where the second plug l placed in the well must pass through the multiple stageunit itmust be of small diameter and of a flexible nature so as to pass through the multiple stage unit. It is incapable, therefore, of scraping the walls of the casing beneath the multiple stage unit to the desired extent.

Other objects and advantages reside in cer-r following description taken in connection with the accompanying drawing,.in which:

Fig. 1 is a vertical cross-sectional view of the casing of an oil well with a multiple stage unit mounted therein and showing two of the plugs used in the cementing operation thereof;

Fig. 2 is a view similar to that of Fig. 1 but showing a second operation of the unitand showing a third plug approaching the multiple stage unit and Fig. 3 is a view similar to that of Fig. 1 but showing the position of the plugs at a still later operation of the unit.

Referring to the drawing in detail, and first to the arrangement illustrated in Fig. 1, a casing of an oil well is there shown as having an upper section II, a multiple stage unit I2, an intermediate section I3 below the multiple stage unit and a lower section I4 to which a floating collar or guide shoe I5 is attached.

The multiple stage unit I2 includes a valve arrangement, port or openings I 6 being provided in the main body of the unit, which ports are normally closed by means of an inner sleeve II held in position by means of shear pins I8. The interior of the sleeve I1 is provided at its lower end with a conical ange or seat Ila for purposes which will presently be described.

` The parts of the multiple stage unit just described are old and well known to those skilled in the art. 'I'he novelty in the present arrangement involves the supporting of a female plug I9 on the upper end of the section I3 of the casing but below the multiple stage unit. To accomplish this the plug I9 has an aluminum or other metallic or hard ring 20 attached thereto at its upper end. This ring 20 has a ange 2| which rests upon the upper end of the section I3 of the casing and holds the plug I9 in place. As shown in Fig. 1, the plug I9 has a central aperture or opening 22 through which cement orlother :duid may pass. In addition the plug I9 has the usual fabric or rubber flexible cups 23 and 24 which aid in maintaining a seal between the plug and the casing.

The plug I9 is mounted in the casing as it is made up and is placed on the upper end of the section I3 just before the multiple stage unit I2 is secured thereto.

In cementing a well with this equipment the slug of cement which is to` pass around the bottom of the casing is first pumped into the Well and this first slug of cement rwhich is to pass around the bottom of the casing is followed by a male plug 25. Mud or other fluid is then pumped into the well and forces the cement downwardly through the female plug I9 and around the bottom of the casing.

The plug 25 is substantially solid in nature and has a depending portion 26 and the usual .flexible cups 21 and 28. The plug 25 passes readily through the multiple stage units, the cup members 21 and 28 being sufficiently flexible toA I1a the plug 29 is provided with a seating member of frusto-conical shape. As this plug seats upon the flange |1a it moves the sleeve I1 downwardly opening the ports I6 sof that the second slug of cement may flow outwardly through the ports I6. The second slug of cement is followed by a fourth plug, designated 3|, in accordance` with usual practice.

In normal operation theplugs I9 and 25 remain in the relative position shown in Fig. 2 after they have once united and pass downwardly through the casing together. Before the plug I9 can pass downwardly the flange 2| must shear off as shown in Fig.'3 and as the plugs I9 and 25 pass downwardly the ring 20 scrapes the wall of the casing'and scours it of all cement which might later harden and interfere with the continued operations in the well'. In order for the flange 2I to shear, the plug 25 must tightly seat against the plug I9 and the pressure created by the pump used in forcing the cement into the well is sufficient to shear the ring 2 I.

To insure the proper' seating of the plug 29 in the sleeve I1, it is desirable to provide means for separating the plugs I9 and 25 should they reach the bottom of the well before the plug 29 reaches its seat on the sleeve I1. To accomplish this the collar or shoe I5 is provided with a centrally disposed stud 32 adapted to contact with the extension 26 on the plug 25 and remove it from its socket in the plug I9, thus-allowing cement to fiow through the passage 22 in the plug I 9. The stud 32 has longitudinal passageways connecting with radial slots, so that fluid` may fiow downwardly through the shoe I5 even through the plug I9 is seated thereon. As stated above, this action takes place only when the plugs` I9 and 25 arrive at the bottom of the well before the plug' 29 is seated. In normal operation the plugs I9 and 25 are not separated.

In the arrangement illustrated, no No. 1 plug is used. That is, there is no plug beneath the ilrst slug of cement which enters the well. If

it is desiredto employ a. No. 1 plug it will be` apparent to those skilled in the art that a female plug corresponding to that shown at I9 may be mounted beneath' the plug I9 and a small male plug adapted to pass through the plug I9 'may be placed in the well beneath the first slug of cement to engage the lower female plug and pass downwardly therewith. It has been found, how-v ever, in normal multi-stage cementing operationsl that it isunnecessary to have a plug pass downwardly beneath the first slug of cement and the arrangement shown in the drawing is sumcient to can'y outa complete multi-stage cementing operation.v

It will be apparent to those skilled in'the art that, although butone embodiment of the invention has been shown and described, herein, various changes may be made in the arrangement and construction of parts `without departing 'from the spirit of the invention or the scope of the annexed claims.

I claim:

1. The combination ,with a casing of an oil well and a multiple stage cementing unit incorporated therein of a male plug and a female plug,

said female plug being mounted in the casing beneath the multiple stage cementing unit and held in position by shearable means, the arrangement being such that the male plug may be pumped down the well behind a slug of cement and contact the female plug to cause the shearing of said shearable means whereupon the female plug may pass downwardly within the casing to scrape the walls of the same.

2. Apparatus for use in the multiple stage cementing of the casing of a well comprising a number of plugs and a multiple stage cementing unit consisting of a structure made up with the casing and having a valve and means adapted to open the valve when one of said plugs contacts the multiple stage unit, one of said plugs having means for detachably mounting the same on the casing beneath the multiple stage unit and another of saidplugs being adapted to pass through said multiple stage cementing unit without opening said valve and to actuate said mounting means to cause the disconnecting of said detachably mounted plug from the casing to cause the detachably mounted plug to pass downwardly and scrape the wall of the casing.

3. Apparatus for use ln the multiple stage cementing of wells, including a casing, having a multiple stage cementing unit, made up with the the same from the casing and to cause the same to pass downwardly within the casing and a plug for causing th'e valve means to open and permit the passage of fluid from the interior of said casing tothe exterior thereofwithout passing around the bottom of the casing.

5. Apparatus adapted for use in oil wells and comprising a casing, valve means mounted therein, a female plug detachably mounted in the casing beneath said valve means, a male plug for contacting the female plug to aid in detaching the same from the casing and to cause the same to pass downwardly within the casing, a plug for causing the valve means to open and permit the passage of fluid froml the interior of said casing to the exterior thereof without passing around the bottom of the casing and means at the bottom of the casing for separating said male and female plugs.

ROLAND E. ODONNELL. 

